The space age, defined as the time during which man had the capability of orbiting objects is now over 20 years old. In that period of time, many objects have been placed into earth orbit, and more recently, a favored type of earth orbit is a synchronous, or more properly, quasi-synchronous earth orbit in which the object placed in orbit appears relatively stationary to an observer on the earth. In the period since the beginning of the space age, the techniques and apparatus employed to place objects in orbit have been refined and developed. Up until quite recently, all launch vehicles were expended during the launching process and therefore the expense entailed in the lauching included the cost of constructing the launch vehicle.
Recently, however, the National Aeronautics and Space Administration (hereinafter NASA) began the development of a reusable launch vehicle, hereinafter referred to as the Space Shuttle. With the advent of this concept, the cost of the launch vehicle can now be spread over the launch of many satellites. In making the capabilities of the Space Shuttle available to industrial concerns, NASA has indicated that the launch cost for any satellite will be related to the cargo carrying capacity of the Space Shuttle which is employed by the satellite. The cargo carrying capacity of the shuttle is based on two factors, namely, weight and volume. To maintain the various payloads independent of each other, the volume factor is computed on the basis of the length of the cargo bay of the Space Shuttle employed.
Ever since the beginning of the space age, it has been a desirable goal for the design of satellites to minimize the weight thereof. Accordingly, a standard practice in designing a satellite is to design the satellite for the minimum possible weight. Therefore, in order to optimize the use of Space Shuttle capacity, the only factor available for adjustment is the length of the cargo bay employed.
Another characteristic one obtains when making lightweight satellites is that their strength or ability to survive loads is limited. Virtually all satellites intended for quasi-stationary orbit carry along with them at least one major source of thrust for orbital insertions as distinguished from a plurality of thrusters of much more limited thrust which are employed to make minor corrections in satellite orbit as well as to control its attitude in orbit. The structural design of the satellite has to take into account the load imposed by its own thrust source or motor and typically the satellite has a thrust axis defined by the orientation of its thrust source along which it is most readily capable of accepting loads.
In mating a satellite to a launch vehicle, it is conventional in the art to align the thrust axis of the satellite with the thrust axis of the launch vehicle. Insofar as I am aware, all previously launched satellites carrying their own major thrust source have been launched in a configuration in which their thrust axis was aligned with the thrust axis of the launch vehicle.
When the Space Shuttle was announced initial proposals for orienting a satellite in the cargo bay of the Space Shuttle employed the conventional technique of aligning the satellite thrust axis with the launch vehicle thrust axis. In some cases, it was proposed, in order to maximize the payload carried by the Shuttle, that several satellites be ganged on a single support and deployment structure. This technique has a number of serious disadvantages. In the first place, the ganged satellites are no longer independent, and a number of serious implications flow from this lack of independence. Firstly, not all satellites in their ganged configuration are available for ready removal. A further and significant disadvantage of stacking, satellites is the unknown interaction between them with reference to mechanical resonance. Thus, careful attention is paid during the design of a satellite to its susceptibility to vibrations at selected frequencies to insure that the vibrations induced during the launch process do not occur at mechanical resonance for the satellite. Without full knowledge of just which other satellites are to be ganged, this precaution cannot be taken and thus one cannot be assured that a satellite pair will not be subjected to vibration that would correspond to a resonance condition of the pair.
To overcome this and similar problems, it was also suggested that the satellite be supported in a cradle tilted at an angle of 43.degree. with respect to the launch vehicle thrust axis. This separated the several satellites and avoided possible resonance effects, but this scheme, too, had a number of drawbacks. In the first place, the several satellites were still not independent in that removal of one or more satellites was required in order to get access to another. Furthermore, and more importantly, the benefits of canting the satellites at 43.degree. were only achieved if all the satellites packed in the Shuttle were likewise canted.
It is therefore an object of the present invention to provide improvements in the methods of supporting satellites in launch vehicles. It is another object of the present invention to provide an improved launch vehicle and at least one satellite supported thereby. It is another object of the invention to provide a satellite in such a launch vehicle which includes a major thrust axis defined by at least one major source of thrust in which the satellite thrust axis is at or about a 90.degree. angle with respect to the thrust axis of the launch vehicle. It is another object of the present invention to provide a method of adapting satellites for effective launch and efficiently utilizing the payload capacity of a launch vehicle in which the satellite has a major thrust axis defined by a major source of thrust and in which that major thrust axis is perpendicular to the thrust axis of the launch vehicle. These and other objects of the invention will become apparent as the description proceeds.